Struct ChangeStore 

pub struct ChangeStore { /* private fields */ }

Invariance

• We don’t allow holes in a block or between two blocks with the same peer id. The Change should be continuous for each peer.
• However, the first block of a peer can have counter > 0 so that we can trim the history.

Encoding Schema

It’s based on the underlying KV store.

The entries of the KV store is made up of the following fields

Key	Value
b“vv“	VersionVector
b“fr“	Frontiers
b“sv“	Shallow VV
b“sf“	Shallow Frontiers
12 bytes PeerID + Counter	Encoded Block

Implementations

impl ChangeStore

pub fn insert_change( &self, change: Change, split_when_exceeds: bool, is_local: bool, )

This method is the only place that push a new change into the change store

The new change either merges with the previous block or is put into a new block. This method only updates the internal kv store.

pub fn get_change(&self, id: ID) -> Option<BlockChangeRef>

pub fn get_change_by_lamport_lte(&self, idlp: IdLp) -> Option<BlockChangeRef>

Get the change with the given peer and lamport.

If not found, return the change with the greatest lamport that is smaller than the given lamport.

impl ChangeStore

pub fn new_mem(a: &SharedArena, merge_interval: Arc<AtomicI64>) -> Self

pub fn get_dag_nodes_that_contains(&self, id: ID) -> Option<Vec<AppDagNode>>

pub fn get_last_dag_nodes_for_peer( &self, peer: PeerID, ) -> Option<Vec<AppDagNode>>

pub fn visit_all_changes(&self, f: &mut dyn FnMut(&Change))

pub fn iter_changes( &self, id_span: IdSpan, ) -> impl Iterator<Item = BlockChangeRef> + '_

pub fn change_num(&self) -> usize

pub fn fork( &self, arena: SharedArena, merge_interval: Arc<AtomicI64>, vv: &VersionVector, frontiers: &Frontiers, ) -> Self

pub fn kv_size(&self) -> usize

Trait Implementations

impl Clone for ChangeStore

fn clone(&self) -> ChangeStore

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for ChangeStore

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.